Dial *121# from your Airtel SIM and check the menu for your number
Dial *282# to display your Airtel mobile number on some networks
Call or send a missed call to another phone and check the number that appears
Check the SIM card pack or welcome letter if you still have it
Open the Airtel Thanks app and view your registered number
Check your phone settings under SIM or About Phone
Contact Airtel customer care from your Airtel SIM and ask for your number
Visit an Airtel store with valid ID and ask them to help retrieve your number